Things like that are great, but they depend on the local conditions being just right. You could have your Skywell, loads of humidity in the air, but if the temperature doesn’t get down to the dew point, you’ve got nothing.
There’s room for clever tricks. You can make ice (and ice cream!) in the desert at night by shielding an area from breezes, letting the heat radiant into the cloudless sky, then covering up during the daytime. Repeat.
Or turn an underground area into a cold sink by only letting in the cooler night air. (Many caves do this naturally because hot summer air can’t sink into the cave, but in winter, when the outside air is colder, the air exchanges. Those icy caves are the work of decades of cold winters.)
